2 x 256 PC2100 Dual Channel or 1 x 512 PC3200 ?

[faster]

I haven't actually taken it apart and put in the chips, but what do you thing would be faster? I have 2 x 256 of Mushkin high performance 2-2-2-5 cas 2 pc2100 ddr and I have 1 x 512 PC3200 ultra cas 2.5 (maybe 3). Which would be faster on the system? The motherboard is a MSI k8n Neo2 Platinum, supporting dual channel memory. This has come up because I canabalized 4 x 512 crucial ballistic pc3200 out of tihs sytem for another 2 systems.

 

[natto fire]

This is not the right forum for this.

To answer your question, (which is poorly worded, you do not state which chip you have and thus we have no idea what FSB you need) go with the higher FSB. Athlons do not benefit much from dual channel, but fairly well with FSB.
Welcome to the forums, but:

Questions regarding troubleshooting, technical support, and product advice belong in other appropriate forums such as General Hardware, Networking, Video, etc. They have more traffic and, they are visited by knowledgable, enthusiastic members eager to share good advice and help troubleshoot problems.